Signaling device for typewriters



Aug. 1, 1939. J. Y. PAYTON SIGNALING DEVICE FOR TYPEWRITERS Filed Aug. 18, 1936 QZJLMQ/J ATTORNEYS Patented Aug. 1, 1939 UNITED STATES; PATENT" 'OFFICE 1 YSIGNALING DEVICE Fort .mnwm'rans James Y, Payton, InsAngeles, Calif. Application August is, 1936, Serial No, 96,631

19 claims. (01,197-189) This invention; relates to signaling devices for typewriters, of the general character embodied in my U. S. PatentNo. 1,945,753, issued February 6, 1934, wherein means is provided to automatically indicate to the typist the proximity'of the typing to the hidden lower edge of the sheet being typed. I

, An object of the present inventionis to pro vide a signaling device which is structurally and )0 functionally characterized to reduce to a negligible minimum such friction as-might tend to adversely aifect the operation of its working parts,

so as to render themechanismsensitive and absolutely positive and dependable in operation in indicating 130 the typist the proximity of the typing to the hidden lower edge of the sheet being typed, and insuch relation thereto that the last'line of the sheet can be safely typed without slipping of the sheet, whereby to enable a neat and uniform lower margin to be' attained on .all sheets, and fullspeed typing maintained through the sheet without risk of running off the lower end of the sheet. 7 L

Another object of the invention is to provide a signaling devicefor typewriters which is comparatively simple in construction; is compactso as to be unobtrusiveand'unobstructive to the normal use of the typewriter, as well as readily adaptable to the typewriter. With these and other objects in view, t e invention consists in the combinations, arrangements and functional relationships of elements 'as set forth in the following specification and particularly pointed out in the appended claims. In the accompanying drawing,

Figure 1 shows in vertical longitudinal section atypewriter platen, with several correlated parts of the typewriter, and showing one form of signaling device embodying this invention applied thereto, W g

Figure 2 is a fragmentary plan view of the signaling device in its association with the platen; Figures 3 and 4 are transverse sectional views taken, respectively, on the lines 3--3'and4-l of Figure 1;

Figure 5 is a transverse sectional view taken on the line 55 of Figure l and illustrating the position of the'signaling device during the typing operation; g Figure 6 is a view similar to Figure 5 but showing a released position of the device;

Figure 7 is a transverse sectional view taken on the line of Figure 1; i V

Figure 8 is a perspective view of a striker em l bodied in the signal;

Figure 9 is a perspective view of a striker actuating cam; i i

s Figure 10is a view similar to Figure 6 show ing a modified form of paper engaging means.

' I Referring specifically to the drawing and par- 5 'ticularly to Figures 1 to 9, inclusive, a typewriter platen P is-fixed to the usual operating shaft 10 journaled in suitable bearings. iI -ll provided on the typewriter :carriage (not shown),-and differs from a conventionalplaten in that, it isli) slightly-reduced in length from its left hand'end for the reception of the signaling device in a manner not to obstruct the normal use of the platen.

' [Firmly seated in an annular recess 12 inthe 15 left hand end of the platen is a cup-shaped memher It forming a pocket adapted to receive, a

portion of the signaling device, the member having-an axial opening through which the shaft l0 projects and has fixed thereto for rotation with 20 I the platen an audible signal. B in the form of abell'll adapted to be sounded by a' striker S.

The striker comprises a length of spring wire one end of which has fixed thereto a striker head IS. The other end of the wire is in the form of a 25 short coil I1 wound in an annular recess I8 formed in the hub I! of the bell so asto be frictially radial portion 2| which is adapted to be utilized to rock :the arm 22 of the striker in a plane substantially parallel to, the axis of the;35

- shaft HI about a fulcrum formed by the first con-' volutionof the coilfrom the portion 2|, and to suddenly release the arm to cause the head Hi to strike the bell .all in a manner to be later l described in conjunctionwith an energy storing 40 .and actuating unit U which is controlled by movements of the platen P and by a'sheet of paper extended around the platenas in typing. The, unit U comprises a ring 23 of a diameter to freely fit within the member l3 and is provided 4J5 with an annular groove 24 receiving a spring 25 'undulated longitudinally and normally tending to expand into engagement with the internal annular surface of the member 13 with sufiicient force to provide a driving connecton between, the 50 platen and ring by which the latter is caused to nomially' rotate with the platen. V

A fiat coil spring 26 is normallyexpanded within the ring and has its outer end fixed in any suitable manner at 21 to the ring. The inner 5 and freely received in a transverse recess end of the spring 26 is similarly fixed at 26 to a portion of a hub 29 projecting from one side of a rotary actuator or disk 30 which is of a diameter to be received in the member 13 alongside the ring 23, and is, by means of the hub, mounted to freely rotate on the shaft Ill.

The other portion of the hub 29 projects from the opposite side of the disk 30 and has threaded thereon so as to solidly abut a shoulder 3| on the hub, a rotary cam 32 provided with an annular rim 33 projecting from one side thereof and having an inclined camming edge 36 extending through an angle of approximately 90 and adapted to bear against the portion 2| oi the striker S. The remaining 270 oi the rim 66 constitutes a low dwell surface, and it will be noted that one end of the latter and the high end of the edge 36 are joined by an axially extending shoulder 66 which is adapted to also co-act with the portion 2| of the striker in a manner to be later described. v

A control member C forming a part of the unit U comprises a disk 66 'having a central opening 31 sufiiciently large to freely receive the hub 29 between the disk 36 andcam'fl so as to mount the disk 36 for transverse or radial movement relative to the platen shait l6. r Y

"At diametrically opposed points, relatively large wheels 36 and 36 are rotatably mounted on the side oi the disk Ill conironting the earn )2. The wheel 36 is straddled by the arms of a yoke 60 projecting from an L-shaped arm ll the free end of which is secured by a set screw 62 to the conventional paper finger carrying shalt 63 which is supported in the bearings il-ll oi the carriage in parallelism with and at the rearoithe platen as will be understood by those familiar with the art.

The yoke 66 which is vertically disposed, coacts with the wheel 36 and with two diametrically opposed and relatively small rollers 66- also on the disk 66, to confine the latter against rotation yet permit transverse or radial movement of the disk.

Under the action of gravity, the disk 66 occupies a lowered position shown in Figure 6 wherein the disk is supported clear of the hub 26 by the rollers 64 which rest upon downwardly and outwardly inclined extensions 66a on the lower ends of the arms oi theyoke 66. In this lowered position of the disk 66, the wheel 66 which is disposedvertically below the wheel 66, has a portion projecting beyond the periphery of the platen); formed in the usual sheet deflector D surrounding the lowermost portion of the platen so as to guide a sheet around the latter, as will be understood. 1

Freely mounted intermediate their ends on pins 66-66 at diametrically opposed points on the disk 66 are curved pawls 61-61 which are thus rockably mounted on the disk to occupy under the action of gravity, either an inactive position wherein their heels" bear against the hub 29, or an active position wherein theirtoes 48 bear against the hub and define substantially radial shoulders on the disk 30, are disposed in the path of movement of a lug 60 projecting from the disk 66, when the latter occupies. its raised position shown in full lines in Figures land 7 under the action of a sheet of paper extended around the platen and engaging the wheel 66, all to the end of providing an operative connection between the disks 66 the heels 66 which missible line is b91118 typed.

and 36 to temporarily prevent theidisk 36 from rotating.

The operation of the invention is as follows:

Prior to the insertion of a'sheet of paper, the control member C will occupy the position shown in Figure 6, wherein the paper riding wheel 39 projects downwardly beyond the periphery of the platen in the normal lowered position of the control member C under the action of gravity, and wherein the lug 60 is clear of the path of rotation of the pawls 61 when occupying their active positions as ai'orestated.

Upon inserting a sheet of paper and initiating rotation 01 the platen P to advance the paper, the wheel 39 will coact with the paper to raise the control member C and hence dispose the lug 66 in the path of the heels .46 of the p' 3115 61 when occupying their active positions. It will be understood that during advancing movement of the platen P, the ring 26 is caused to rotate with the platen because of the frictional driving connection between the ring and platen provided by the undulated spring 26 wrapped around the ringin its groove 26.

Now, as advancing movement of .the platen is continued, the first one'of the .pawls 6.1 which approaches the lug 60 is rocked bygravity to its active position so that its heel is will engage the lug and thus arrest rotation of the disk 30, to thereby initiate winding or loading oi the coil spring 26, asit willberemembered that the inner end of this spring is fixed to the huh I! of the disk 66, and the outer end oi the spring isfixed tothering 26. l

As the cam "is now also held against rotation, and as the bell B is being rotated by the platen, the portion ll oi the striker S, in riding upon the camming edge 64 towards its low terminal, will engage the shoulder 66 of the cam so as to arrest .further rotation of the striker by the bell. It will be appreciated that as continued rotation of ,the bell under advancing movement of the platen tends to unwind the coil 11 of the striker S in the recess I6 01 the bell hub II, that the hub is free to slip within the coil and thus not restrict such rotation of the bell.

As advancing movement 01 the platen is continued step by step'during the typing operation,

the spring 26 is being wound to thus store up energy therein. When the bottom edge of the paper reaches a point below the platen at which the wheel 36 is cleared, the control member C is thus rendered free to gravitate instantly to its lowered position shown in Figure 6, thereby disengaging the lug 66 from that one of the pawls 41 with which it has been co-acting to arrest rotation of the disk 66. I

As the disk is now free for rotation, the energy stored in the spring 26 by the winding of the spring during advancing movement of the platen,

instantly manifests itself by rotating the disk SI the portion 2| 0'! the striker s, and the rim u of the cam to traverse the portion 2|. As the' inclined camming edge flot theicam traverses the portion- 2 I the striker arm isstressed laterally so that when the high terminal of the camming edge leaves the portion ii, the striker arm will be suddenly released for the striker head l6 to strike .the bell B and thus produce a clearly audible signal to. the operator that the last per- Should the sheet of PM! being typed exeffected without any harm to'the mechanism as ceptionally long, with the result of fully winding the spring 28 during advancing movement of the platen, the spring 25 will yield so as to permit the ring 2: to slip within the cup member It, thus positively preventing overwinding and breakage of the spring 26.

, It is also to be noted that the length of the dwell surface on the cam rim SI is calculated to insure that notwithstanding the speed [of rotation 'of the cam 32 by the spring 26 when the control member is tripped, the ball will have been struck before the cam can have made'a second advanced to the predetermined position; and means for -preventing overwinding of the spring in the event that the sheet is of such length that the spring has been fully wound before the bottom edge of the sheet reachesthe aforestated predetermined position. 1 i i Y 3. In a typewriter, a platen; asignal. comprising'a bell and ajstrikerxior sounding the bell; a

rotary actuator having means for energizing and releasing-the striker to" sound the bell in. re-

sp nse to rotation} of: the actuator in one direction a spring ,operatively' connecting the platen androtary' actuator and adapted to be wound wherithe platen is rotated toadvance a sheet of paperand said actuator is held against rotation; means controlled by a sheetof paper to prevent rotation by the spring according as the paper is co-act with the downwardly and outwardly inclined extensions 40a to maintain the control member against tilting as a sheet of paper is, inserted and strikes the wheel 39, thus facilitatingraising of the control member, by the paper.

Retrograde movement of the platencan be thepawls 4] merely rock clear of the lug 50 during'such movement of the platen.

By reference to Figure 10, it will be noted that for platens of lesserdiameter curved approach members 5l-5l can be fixed at 52 on the thereb'etween. The members 5i smoothly guide a sheet beneath the wheel during control member C to freely receive the wheel I! function to the operation of inserting the-sheet from the front or back side oi the platen, thus facilitating the insertion oi: the sheet. 1 In the larger sized platens, the approach members and are dispensed with.

What is claimed is: I

1. In a typewriter, aplaten; a signal comprisare unnecessary extended around the platen or the lower edge of the sheet reaches a predetermined position, wherebyto 'wind the'spring during the typing operation and tosound the signal when the sheet has been advanced to the predetermined position; andafrictional driving connection for the spring between the platen and said actuator normally enabling the spring to be wound in response to advancing movement of the platen yet yielding when the spring has been wound tosuch extent that'further winding mightcause breaking of the spring.

: 4.-'In a typewriter, a platen; asignal comprising a bell and a striker for sounding the bell; a rotary actuator havingan annular cam co-act- 1 rotation of the said actuator or free the latter for' ingwith the striker to stress and then release the latter for striking or thebell, in response to direction; a spring rotation of the actuator in one operatively connecting the platen and rotaryactuator and adapted to bewound when the platen is rotated to advance a sheet of paper and said actuator is held against rotation; a control meming a bell and a striker for sounding the bell; a

rotary actuator having means for energizing and releasing the striker to sound the bell in response to rotation of the actuator in one direction; a spring operatively connecting the platen and rotary actuator and adapted to be wound when the platen is rotated'to advance'a sheet of paper and said actuator is held against rotation;

and means controlled by a sheet of paper to prevent rotation of said actuator .or. free the latter for rotation by the spring-according as the paper is extended around the platen or the lower edge of the sheet reaches a predetermined position,

whereby to wind the spring during the typing operation and to sound the signal when the sheet has been advanced to the predetermined position 2. ma typewriter, a platen; a signal comprisber mounted for movement transversely of the platen axis to occupy either of two extreme positions; meanson the controlrnember adapted to co-act with a sheet of paper. when extended around the platen in moving the control member to one extreme position; and co-acting means on the control member and rotary actuator by which rotation of the latter-is prevented when the control member occupies said one extreme position, or the actuator released for rotation 1 when the control member'occupies its other extreme position, whereby to energize the spring during the typing operation and to sound the signal when the bottom edge of the sheet clears said paper co-acting means. i

5. In a typewriter, a platen; a signal comprising a belland astriker for sounding the bell; a

rotary actuator having an annular cam co-a'cting with the striker to stress and then release the I latter for striking oi the bell, in response to rotaing a bell and a strikerfor sounding the bell; a

.rotary actuator having means for energizing and releasing the striker to sound the bell in response to rotation of the actuator in'one direction; a

spring operatively -connectlng the platen and rotary actuator and adapted to be wound when the platen is rotated to advance a sheet of paper controlled by a sheet of paperto prevent rotation of said actuator or free the latter for rotaand said actuator is held against rotation; means tion by the spring according as the paper is ex-' tended around the platen or the lower edge of the sheet reaches a predetermined position, whereby to wind the spring during the typing operation and to sound tlre 18ml when the sheet has been tion of the actuatorirr one direction; a spring operatively' connecting the platen and rotary actuator and adapted to be wound when the platen is rotated to advances. sheetof paper and said actuator is held against rotation; a control member mounted for movement transversely of the platen axis to occupy either oftwo extreme positions; means on the control member adapted to eoact with a sheet of paper when extended around the platen in movingthe control-member to one extreme position; and co-acting lug and pawl means on the. control member and rotary actuator by'which rotation at the latter is prevented when the control member occupies said I one extreme position, or the actuator released for rotation when the control member occupies its other extreme position, whereby, to energize the spring during the typing operation and to 'sound the signal. when the bottom edge of the sheet clears said paper coacting means.

6. In a typewriter, a platen; a signal comprising a bell and a striker for sounding the bell; a rotary actuator'having means for energizing and releasing the striker to sound the bell in response to rotation of the actuator in one direction; a

' spring operatively. connecting the platen and axis to normally gravitate to alowered position;

' rotary actuator having means 'paper riding wheel on the tion of the latter is prevented means on the control member adapted to co-act with a sheet of paper when extended around the platen, in moving the control member to a raised position; and co-acting means on the control member and rotary actuator by which rotation of the actuator is prevented or permitted according as the control member occupies raised or lowered position, whereby to wind the spring during the typing operation and to sound the signal when the bottom edge of the sheet clears the paper co-acting means.

'7. In a typewriter, a platen; a signal comprising a bell and a striker for sounding the bell; a rotary actuator having means for energizing and releasing the striker to sound the bell in response to rotation of the actuator in one direction; a

spring operatively. connecting. the vplaten and rotary actuator and adapted to be wound when the platen is rotated to advance a sheet of paper and said actuator is held against rotation; a control member; a wheel on the control member and a fixedly mounted yoke straddling thewheel for co-action therewith in preventing rotation, of the control member while mounting the latter for vertical movement transversely of the platen axis to normally gravitate to a lowered position; a control member adapted to co-act with a sheet when extended around the platen, in moving the control member to a raised position; and co-acting means on the control member and rotary actuator by which rotaor permitted according as the control member occupies raised or lowered position, whereby the spring will be wound during the typing operation and the signal will be sounded when the bottom edge of the sheet clears the paper riding wheel. i

a 8. In a typewriter, a platen; a signal comprising a bell and astriker for sounding the bell; a

releasing the striker to sound the bell in response to rotation of the actuator in one direction; a spring operatively connecting the platen and rotary actuator and adapted to be wound when the platen is rotated to advance a sheet of paper and said actuator is held against rotation; a control member; a wheel on the control member and a fixedly mounted yoke straddling the wheel for co-action therewith in preventing rotation of the control member while mounting the latter for vertical movement transversely of the platen axis to normally gravitate to a lowered position; a paper'riding wheel on the control member adapted to co-act with a sheet when extended around the platen, in moving the control member to a raised position; co-acting means on the control member and rotary actuator by which for energizing and 7 rotation of the latter is prevented or permitted according as the control member occupies raised or lowered position, whereby the spring will be wound during the typing operation and the signal will be sounded when the bottom edge of the sheetclears the paper riding wheel; rollers on the control member engaging the arms of said yoke at their outer sides for co-action with the first mentioned wheel in guiding the control member vertically; and means on the yoke co-acting with said rollersto suspend the control member in its lowered position. I g

9. In a typewriter, a platen; a signal comprising a bell and astriker for sounding the bell; a rotary actuator having means for energizing and releasing thestriker to sound the bell in response trol member; a wheel on the control member and a fixedlymounted yoke straddling the wheel for co-action therewith in preventing rotation of the control member while mounting the latter for vertical movement transversely of the platen axis to normally gravitate to a lowered position; a

paper riding wheelon the control member adapted to co-act with a sheet when extended around the platen, in moving the control member to a raised position; co-acting means on the control member and rotary actuator by which rotation oi the latter is prevented or permitted according as the control member occupies raised or lowered position, whereby the spring will be wound during the typing operation and the signal will be sounded when the bottom edge 01' the sheet clears the paper riding wheehrollers on the control member engaging thearms of said yoke at their outer sides for co-action with the first mentioned wheel in guiding the control member vertically; and downwardly and outwardly inclined extensions projecting from the yoke arms and on which the rollers ride for co-action therewith in suspending the control member in lowered position and guiding the control memberagainst tilting movement.

10. In atypewriter, a rotatably mounted shaft; a platen fixed to said shaft and-having an annular pocket in one end; a bell mounted on the shaft; a

striker having a resilient arm and correlated withthe bell to strike the latter; a ring moun'tedin said pocket and having an annular groove; a spring seating in said groove and engaging the wall of said pocket to provide a friction driving connection between the platen and ring; a disk rotatably mounted in the pocket; a coil spring connected f to the ring and disk'for winding of said spring when the platen is rotated to advance a sheet of paper and said disk is held against rotation; a control member mounted for movement transversely of the platen axis to occupy raised and lowered'positions, and having means adapted to co-act with a sheet of paper when extended around the platen, in moving the control member to its raised position; co-acting means on the control member and disk by which rotation of the latter is prevented or permitted according as vthe control member occupies raised or lowered position; and means on the disk responsive to rotation of the disk under the action of the coil spring, to co-act with the striker arm in stressing and then releasing the latter to strike the bell.

11. In a typewriter, a rotatably mounted shaft;

a platen fixed to said shaft and having an annular pocket in one end; a bell mounted on the shaft; a

striker having a resilient arm correlatedwith the bell to, strike the latter; a ring mounted in said pocket and having an annular groove; 9.

spring seating in said groove and] engaging the wall of said pocket to provide a friction driving connection between the platen and ring; disk rotatably mounted in the pocket; a coil spring,

connected to the ring and disk forwinding of said spring when the platen is rotated to advance a sheet of paper and said disk is held against rotation; a control member mounted for moye.-. ment transversely of the platen axis to occugy;

raised and lowered positions, and having me adapted to co-act with a sheet of paper when extended around the. platen, in moving the con-j or lowered position; andan annular cam on said disk, bearing-against thestriker arm to stress and-release the latter in response to rotation of the disk under the action of the coil springJor,

I sounding of the bell by the striker.

12. In a typewriter, a rotatably mounted shaft; a platen fixed to said shaft and having an annular pocket in one end; a bell mounted on the shaft; a striker having a resilient arm and correlated with the bell to strike the latter; a ring mounted in said pocket and having an annular groove; a spring seating in said groove and engaging the wall of said pocket to provide a friction driving connection between the platen and ring; a disk rotatably mounted in the pocket; a coil spring connected to the ring and disk for winding of said spring when the platen is rotated to advance a sheet of paper and said disk is held against roaround the platen, in moving the control member to its raised position; a lug on the control member and pawls on the disk coacting toprevent or permit rotation of the latter according as the control member occupies raised or lowered position; and means on the disk responsive to rotation of the latter under the action of the coil spring, to co-act with the striker arm in stressing and then releasing the latter to strike the bell.

13. In a typewriter, a rotatably mounted shaft; a platen fixed to said shaftand having an annular pocket in one end; a bell mounted on the shaft; a striker having a resilient arm and correlated with the bell to strike the latter; a ring mounted in said pocket and having an annular groove; a

spring seating in said groove and engaging the wall of said pocket toprovide a friction driving connection between the platen and ring; a disk rotatably mounted in the pocket; a coil spring connected to the ring anddisk for winding of said spring when the platen is rotated to advance a sheet of paper and said disk is held against rotation; a control member mounted for movement transversely of the platen axis to occupy raised and lowered positions, and having means adapted to co-act with a sheet of paper when extended around the platen, in moving the control member to its raised position; co-acting in stressing Tand then releasing the latter to strike the bell; said bell having a hub by which it is fixed to the shaft; and said striker arm ha'v I ingv a portion coiled'about the hub' to mount the striker thereonyetperniit the bell to be rotated with the platen during advancing movement of the latter, without rotating the striker.

14. In a typewriter, a rotatably mounted shaft;

a platen fixed to said shaft and havingan annu lar pocket in one end; abell mounted on the shaft; a striker having aresilient-arm and cor related "with the bell to strike the latter; aring mounted in said pocketand having an annular groove; 9. spring seating insaid' groove and engaging the wall of said pocketto provide a frie ti'on driving connection 'between the platen and ring; a disk rotatably mounted in the pocket; 9. coiljspringconnected to the'ring and disk for windingof said spring whenthe platen is rotated to advance a; sheet of paper and saiddisk is held against rotation; a controldisk havinga wheel; a fixedly'mounted yoke the arms of which straddlesaid wheel for co-action therewith in mounting the control disk for vertical movementgtransversely of the platen a'xisto normally gravitate to a lowered'position; a' paper riding wheel car ried by the control disk and adapted to co-act with a sheet of paper to move the control disk to a raised position; means onthe first disk and the control disk co-acting to prevent or permit rotation of the first disk according as the control disk occupies raised or lowered positions; and

means on the first disk responsive torotation of the latter under the action of the coil spring, to coact with the striker arm in stressing and re" leasing the latter to strike the bell.

15. In a typewriter, a rotatably mounted shaft; a platen fixed to said shaft and having an annular pocket in one end; a bell mounted on the shaft; a striker having a resilient arm and correlated with the bell to strike the latter; a ring mounted in said pocket and having an an-- nular groove; a spring seating in said groove and engaging the wall of said pocket to provide a friction driving connection between the platen and ring; a disk rotatably mounted in the pocket; a coil spring connected to the ring and disk for winding of said spring when the platen is ro tated to advance a sheet of paper and said disk is held against rotation; a control disk having a wheel; a fixedly mounted yoke the arms of which straddle said wheel for co-action'thcrewith in mounting the control disk for vertical movement transversely of the platen axis to normally gravitate to a lowered positioma paper riding wheel carried by the control disk and adapted to co-act with a sheet of paper to move the control disk to a raised position; means on the first disk and the control disk co-acting to prevent or permit rotation of the first disk according as the control disk occupies raised or lowered position; means on the first disk responsive to rotation of the latter under the action of the coil spring, to co-act with the striker arm in stressing and releasing the latter to strike the bell; guide rollers on the control disk engaging the yoke arms atthe outer sides thereof; and lateral extensions on the the platen is rotated to advance a sheet of paper,

and said actuator is held against rotation; and, means controlled bythe paper to prevent or perholding the actuator against rotation by the first means; means including. a paper riding wheel by which the actuator iscaused to be released for rotation by the first means when the lower edge of a sheet reaches a predetermined position around the platen, whereby to activate the signal; and approach members freelyv receiving said wheel therebetween and adapted to smoothly guide a sheet beneath the wheel when inserting the sheet from the front or back of the platen.

18. In a typewriter. a platen; a signal; a rotary actuator for activating-the signal in response to rotation of in one direc-.

tion; a spring-adapted to be wound to store energy when the actuator is held from rotating during paper advancing movement of the platen; means for holding the actuator against rotation; means for releasing the actuator when the lower edge of a sheet reaches a predetermined position around the platen, whereby to enable the spring to unwind and rotate the actuator so as-to activate the signal; and means for preventing overwinding oi the spring.

19. In a typewriter, a platen; a signal; a rotary actuator for activating the signal in response to rotation of the actuator inone direction; a spring adapted to be wound to store energy when the actuator is held from rotating during paper advancing movement of the platen; means for.

holding the actuator against rotation; means (or releasing the actuator when the lower edge of a sheet reaches a predetermined position around the platen, whereby to'enable thespring to unwind and rotate the actuator so as to activate the signal; and a yieidable driving connection between the platen and actuator operable to prevent overwinding of the spring.

JAIN Y. PLYIDN. 

